Gulf of Maine will become too warm for many key fish, report says

Shawn Keppler guides a bucket of cod out of the hold of the Jamie & Ashley at the Portland Fish Pier in 2014. Staff file photo by Gregory Rec

A new study by federal fisheries scientists predicts the warming of the Gulf of Maine will cause a dramatic contraction of suitably cool habitat for a range of key commercial fish species there. On the other hand, lobsters are more likely to find hospitable areas.

The study by seven scientists at the National Oceanic and Atmospheric Administration’s Northeast Fisheries Science Center in Woods Hole, Massachusetts, used a high-resolution global climate model and federal fisheries survey data to model how key fisheries species would likely be affected by predicted warming over the next 80 years.

The results confirmed previous research using other models and methods that found that the Gulf of Maine can be expected to become increasingly uncomfortable for many of the cold-loving species that have thrived here for all of recorded history but are at the southern ends of their ranges. Those include cod, haddock, redfish, plaice and pollock.

“The main message here is how important it is to understand the potential magnitude of the changes that you see when you get a finer, higher-resolution view of the implications of changing sea temperatures,” says co-author Michael Fogarty, chief of the ecosystem assessment program at the Northeast Fisheries Science Center.

The scientists caution that the research analyzes just one factor – albeit an important one – the distribution of thermally appropriate habitat for each of 58 species. Their results predict the changes in the amount and location of such habitat but don’t account for many other factors that can influence the future populations of the species themselves, such as what happens to what they eat or what likes to eat them, or how the increasing acidity of the ocean – another product of climate change – will affect each.

“This is not telling you that in the future this is what the species’ abundance and distribution will be, only how much suitable thermal habitat each has,” says lead author Kristin Kleisner, who recently joined the staff of the Environmental Defense Fund and is based in Boston. “A lot will depend on how these species shift and the interactions they have with other species.”

The results are sobering nonetheless.

Some of the 600 lbs of haddock, pollock and cod that commercial ground fisherman Tim Rider and crew caught using rod and reel 61 miles out in the Gulf of Maine in January are packed and ready to deliver to restaurant clients. Staff file photo by Carl D. Walsh

Animated maps at the science center’s website show the habitat of the suitable temperature for many species shriveling away to nothing in the Gulf of Maine 80 years from now, as surface temperatures increase. Among the losers are most of the groundfish that were once the mainstay of New England fishermen: cod, pollock, haddock, hake, flounder and redfish.

It is not clear whether some of these cold-loving species might find refuge in colder waters in Atlantic Canada, because the researchers’ data are confined to the United States. “The picture could look a lot different if we had been able to look outside the U.S. Northeast and had Canadian surveys,” Kleisner says.

Kathy Mills, a scientist at the Gulf of Maine Research Institute in Portland who was not involved in the research, says the paper is an important step toward understanding the role climate change in playing in the gulf, though she cautions that the models are not comprehensive enough to serve as advice for what individual communities should expect will happen with a given fishery.

“This paper is putting a lot of really good data on the table,” Mills says. “But there’s a real need to figure out how to apply that information, and how to translate it to locally relevant measurements.”

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Previous studies have had to rely on global climate models that generally have a 62-by-62-mile resolution – so coarse that even a feature as large as Georges Bank isn’t accounted for, throwing off circulation modeling in the Gulf of Maine. But a high-resolution model – called CM2.6 – has a 6.2-by-6.2-mile resolution, allowing much more accurate predictions in New England, says Vince Saba, who works with it at NOAA’s Geophysical Fluid Dynamics Laboratory in Princeton, New Jersey, where it was developed. The higher definition allows the model to “see” and account for not only Georges Bank but other topographic and bathymtric – ocean-floor topographic – features that influence how ocean currents circulate through the gulf.

It’s also allowed for better predictions of how much the surface of the Gulf of Maine will warm: 6.7 degrees Fahrenheit over the next 80 years, or twice the rate of warming documented over the past 30 years.

While that increase will pinch many groundfish, the new research predicts a substantial increase in thermally appropriate habitat for American lobster, overwhelmingly the most important fishery in Maine in the decades since the collapse of many groundfish stocks. Longfin squid, previously rare in Maine, would see much of the gulf open up to them as it warms over the second half of the century.

Cory McDonald pulls lobster out of a trap while fishing off the coast of Stonington in 2015. Over the past two decades, the lobster population in the Gulf of Maine has doubled to 250 million adult lobsters, even as the lobster catch has tripled. Robert Steneck, a lobster researcher at the University of Maine’s Darling Marine Center, believes the lobster population has boomed because a primary predator of lobster, cod, has been decimated in the Gulf of Maine. Staff file photo by Gregory Rec

The researchers caution that thermal habitat is just one part of the picture.

“For lobsters, there can be synergies between warming and disease like shell rot but also with species interactions,” says Saba, one of the co-authors of the study, which was published in the latest issue of the scientific journal Progress in Oceanography. “In Long Island Sound right now, even if there were some sort of recovery of the lobster population, it’s not going to happen because they are getting all these warmer species of fish like black sea bass and striped bass there that like to eat baby lobsters.”

Since 2004 the Gulf of Maine – which extends from Massachusetts to the head of the Bay of Fundy and includes all of coastal Maine – has warmed faster than anyplace else on the planet, except for an area northeast of Japan, raising concerns about the long-term stability of its traditional fisheries and ecosystem.

The Geophysical Fluid Dynamics Laboratory is part of NOAA’s Office of Oceanic and Atmospheric Research, which President Trump has targeted for a 26 percent budget cut. NOAA’s satellite division, which provides essential climate observations, is due to be cut by 22 percent.